In terms of their diagnostic classifications, anxiety disorders and depressive disorders occupied two totally separate diagnostic categories in the American Psychiatric Association’s diagnostic manual The Diagnostic and Statistical Manual for Mental Disorders – Fifth Edition(DSM-5).
However, the order of the diagnostic categories is presented in such a manner that disorders that are somehow related or share a number of different features are placed close to one another. In the DSM-5, the diagnostic categories of depressive disorders and anxiety disorders are placed side by side, indicating that these disorders do share a number of different features and general relations, and at the same time represent separate diagnostic categories of mental illnesses.
The terms depressive disorders and anxiety disorders are not quite the same thing as depression and anxiety. Depressive disorders and anxiety disorders represent discrete categories of mental health disorders that must meet certain diagnostic features, whereas the terms depression and anxiety describe discrete, separate, and very subjective physiological and emotional experiences. Most everyone experiences feelings of depression and anxiety at one time or another, but very few are diagnosed with a depressive disorder or an anxiety disorder.
The experience of depression includes some form of sadness, whereas the experience of anxiety is comprised of some type of a fearful or nervous feeling. Both of these can present with a number of other symptoms and even present in an atypical manner, such as an irritable type of depression where the individual does not experience a preponderance of sadness, but instead expresses irritability that is fueled by sadness. Anxiety can also present in an atypical manner, where the individual presents primarily with an irritable or aggressive presentation that is fueled by deeper feelings of fear.
While these two emotional feelings are considered to be qualitatively different in their subjective experience, it has long been recognized that elements of depression and anxiety can be found in the presentation of nearly every identified mental health disorder. For example, in his classic work Differential Diagnosis in Clinical Psychiatry, the imminent psychiatrist Dr. Paul Hoch made a point to mention that there were elements of anxiety and depression to be found in every individual who is diagnosed with a psychiatric disorder. This relationship remains true today. For instance, many current psychological disorders have elements of depression and anxiety in their presentation.
- Anxious depression: Some individuals who are diagnosed with depression present in a manner that is more consistent with feeling anxious instead of sad.
- PTSD: A completely different classification of disorders in the DSM-5, the Trauma – and Stressor-Related Disorders includes such disorders as post-traumatic stress disorder, where individuals present with serious manifestations of depression and anxiety, and may also receive separate diagnoses of depression and an anxiety disorder.
- Personality disorders: The personality disorders as classified in the DSM-5 all have elements of both anxiety and depression in their presentation.
- ADHD: Even disorders that appear in children and have no diagnostic criteria describing depression or anxiety, such as attention deficit hyperactivity disorder, are known to be associated with the presence of anxious and depressive states.
- Comorbidity: The term comorbid essentially means two or more separate diagnoses that occur together or are diagnosed together. A large number of individuals diagnosed with anxiety disorders are also diagnosed with depression, and a large number of individuals diagnosed with depressive disorders are also diagnosed with an anxiety disorder.
Thus, even though the subjective experience of anxiety and depression represent two qualitatively different emotional occurrences that are interrelated and often occur together in all manifestations of behavioral psychopathology. One can find elements of anxiety and depression in nearly every diagnostic category in the DSM-5. In addition, many of the diagnostic categories have an option for diagnosing the disorder with either a depressed or anxious presentation or have significant comorbidity with both depression and anxiety. Thus, depression and anxiety share significant relationships as general symptoms associated with nearly all forms of psychopathology.
It is interesting to note that there have been relatively few studies that compare the neurobiology of anxiety and depression across groups of patients expressing specific types of anxiety disorders or depressive disorders. However, an interesting report in the journal Dialogues in Clinical Neuroscience speculates that an area of the brain known as the amygdala may play an important part in the presentation of certain types of anxiety disorders as well as depression. In addition, it is well established that areas of the prefrontal cortex, the temporal lobes, and other certain cortical and subcortical structures in the brain (below the level of the cortex in the brain) have been identified as being important in the manifestation of both anxious and depressive behaviors.
Another interesting piece of evidence that anxiety and depression may share similar neurobiological substrates (at least in some cases) is the notion that several types of medicines developed for the treatment of depression (e.g., selective serotonin reuptake inhibitors) also have important treatment implications for various types of anxiety disorders or other mental health disorders where anxiety plays an important role. Thus, certain neurotransmitters such as dopamine, serotonin, and norepinephrine, are most likely important in aspects of the presentation of both depression and anxiety.
In many cases, having an anxiety disorder may lead to the development of the depressive disorder, and having a depressive disorder may lead to the development of anxiety or an anxiety disorder. For instance, individuals who have panic disorder often develop depressive symptoms as a result of their limitations associated with behaviors designed to avoid or anticipate panic attacks. Individuals who are diagnosed with depression often develop anxiety regarding negative beliefs they have about themselves, other people, or their future.
Individuals who are diagnosed with anxiety disorders and depressive disorders often display very similar types of irrational and negative thought processes. For instance, many individuals with anxiety disorders have certain fears regarding the future, whereas many individuals with depressive disorders feel hopeless or full of despair. The manifestations of anxiety and depression will often share similarities in their physical symptoms, such as headaches, muscle cramping, bodily aches and pains, nausea, fatigue, and hypervigilance. People who are diagnosed with severe medical disorders, such as arthritis, cancer, HIV, etc., often display co-occurring issues with anxiety and depression as a reaction to both the physical manifestations of their illness and their beliefs and expectations regarding their future.
Treatment for Depressive Disorders and Anxiety Disorders
Anxiety disorders and depressive disorders both respond to a number of different interventions. These include:
- Medications: There are a number of different classes of medications that are used to treat anxiety. Most often, benzodiazepines or certain types of antidepressants are used in the treatment of anxiety. Depression responds to a number of different classes of medication developed specifically for the treatment of depression, such as selective serotonin reuptake inhibitors, newer atypical antidepressants, tricyclic antidepressants, and other medications.
- Therapy: Both anxiety disorders and depressive disorders have very good response rates to a number of different types of therapy. Cognitive Behavioral Therapy is often used in the treatment of both of these disorders. While the same general principles apply in the delivery of the therapy across all cases, specific disorders do require specified adaptations of Cognitive Behavioral Therapy to address the particular presentation of the individual.
- Lifestyle changes: Both anxiety disorders and depressive disorders respond to a number of positive lifestyle changes. These responses occur to varying degrees depending on the individual and the specific case. However, individuals going on a program of exercise, meditation, or diet changes will often experience a reduction of their anxiety or depression. Other important lifestyle changes that contribute to a reduction in anxiety and depressive symptoms include social support, important interpersonal relationships, and developing a purpose or focus in life.
Anxiety and depression represent mutually exclusive forms of subjective emotional experiences that are qualitatively different; however, they share a number of interrelations, including their tendency to co-occur, having several similar neurological substrates, responding to similar forms of medication, and presenting in similar fashions. While anxiety and depression do share a number of features and have a number of significant interrelations, they are not different manifestations of the same thing.